This invention relates generally to die conveyors used with automated pick-and-place equipment requiring the manipulation of numerous die at high speeds, and more particularly to a novel nest for holding a die against a vacuum port and releasing same without an independently controlled vacuum source, and an elevator mechanism employed to lift the nest to a pick location accessible by the host pick and place equipment.
The present invention is an improvement of die or component conveyors used with automated pick-and-place equipment, particularly those systems requiring the manipulation and placement of numerous die or components at high speeds. The present invention includes, among other aspects and features, a novel nest for holding a die against a vacuum port and releasing it without an independently controlled vacuum source. The invention also includes a novel elevator mechanism, employed to lift the nest to a pick location and means for positioning and aligning the nest for precision travel and pick location placement.
This present invention is considered an improvement over die conveying systems for feeding die directly from a wafer to high-speed circuit board manufacturing equipment, including other direct die feeders. The prior direct die feeders generally rely on conveyor or belt transport technology to convey die to a pick location at the distal end of the feeder. In many applications, conveyors have proven to be unsatisfactory when conveying die or components having dimensions of less than about 1.0 millimeter. To overcome this problem, the present invention is directed to a high-speed shuttle transport system as a replacement to a conveyor or belt transport system as disclosed in the applications cited above. While the shuttle is capable of handling much smaller and larger die than the conveyor, it may not be able to match the throughput capabilities of a conveyor system. Thus, depending on the application, either a conveyor or shuttle may be a preferred apparatus.
In accordance with the present invention a shuttle unit preferably has two parts including a carriage and a shuttle nest assembly. As described herein, the shuttle nest carriage is slideably mounted on a pair of parallel rails extending the length of the feeder, and the shuttle nest traveling thereon is accurately positioned using a belt and pulley system and stepper motor as is well known for the movement of carriages in computer printers and scanners.
The shuttle nest assembly is generally brick-shaped and generally horizontally disposed over the carriage, and is mounted to the carriage by a plurality of pivotable links to permit the shuttle nest assembly to be elevated with respect to the carriage. The shuttle nest assembly also carries a plurality of nests disposed in a line. Each nest has an up position and a down position and can carry at least one die or component on an upper nozzle surface thereof. When in the up position, each nest""s vacuum port is in communication with a vacuum source that is preferably a common vacuum source for all the nests.
When in the down position, the nest""s vacuum port is disconnected from the vacuum and is in communication with atmospheric pressure. In operation, the nest is reset into the up position using pneumatically actuated reset pins or similar means so as to put the upper nozzle surface in a die receiving position and allowing the nest to be placed under vacuum, albeit open to atmosphere until a die is placed thereon. Once in the up position, the nest is ready to receive a die. When a die is placed in contact with the nest""s vacuum port, the die will remain in place on top of the nest until the nest is pushed down, which vents the nozzle to atmosphere and release the vacuum, thereby releasing the die. It is contemplated that a pick and place machine of the type used in the manufacture of circuit boards will push the nest down, thereby releasing the die from the nest, as it is removing the die from the nest.
In accordance with the present invention, there is provided a die conveying apparatus in a die feeder, comprising: a fixed path in the die feeder, said path lying between a first location in proximity to a die source and a pick location at an end of the feeder; and a shuttle generally translating along said path for transporting die from the first location to the pick location, said shuttle carrying a plurality of nests, each of said plurality of nests being capable of holding a die thereon.
In accordance with another aspect of the present invention, there is provided a nest capable of holding a single die against a vacuum port on a surface thereof and releasing said die without requiring an independently controlled vacuum source, said nest comprising: a vertically disposed post; and a nest housing, wherein the post is mounted for vertical movement along a longitudinal axis of the post between an up position and a down position relative to said nest housing, said post having a continuous airway extending therethrough from a port at its upper end to an orifice on a side of the nest between the upper end and a lower end thereof, and when said post is in the up position said orifice is aligned with a passageway communicating with the vacuum source so as to produce a vacuum at the port, and when said post is in the down position, said orifice is disengaged from the vacuum source and the airway communicates with air at atmospheric pressure, thereby releasing the die from the port.
In accordance with yet another aspect of the present invention, there is provided a die conveying apparatus in a die feeder, comprising: a fixed path in the die feeder, said path being a linear path between a first location in proximity to a die source and second location in proximity to a pick location at an end of the feeder; a shuttle carriage, slidably connected to said fixed path and traveling therealong; and a shuttle operatively associated with said shuttle carriage, wherein said shuttle is conveyed along a non-linear path as the carriage travels along the fixed path, thereby transporting die from one of a plurality of shuttle positions adjacent the die source to the pick location, said shuttle carrying a plurality of nests, each of said plurality of nests being capable of holding a die thereon.
One aspect of the invention is based on the discovery of techniques for independently controlling the application of a vacuum source to individual die nests based upon a position of the nest, and the transport of die from a placement location to a pick location. The techniques enable the use of a shuttle die transport system as a replacement for convention conveyor or belt-type systems. Because of the accuracy of placement, and the retention of die on a shuttle nest using vacuum, the system is highly accurate and increases the pick-up efficiency of the assembly machine to which components are being fed. Moreover, the novel vacuum valving design enables to shuttle to be constructed without an elaborate valve control system, saving both cost and precious space in the die feeder.